The present invention relates to a device for automated processing of an unmeasured sample of whole blood into measured multiple aliquots of plasma, and to a method for accomplishing such processing.
To analyze a sample of whole blood for its chemical content, it is first necessary to separate the liquid plasma component from the solid cellular component, and then to divide the plasma into discrete aliquots for further processing. Traditionally, this is a multistep, labor-intensive process which requires not only manual operations, but also some type of pipetting equipment for the final aliquoting step. As a result, the existing methods and equipment for preparing aliquots of plasma from whole blood are expensive and inefficient.
Centrifugal fast analyzers are known devices. For example, see U.S. Pat. Nos. 3,555,284; 3,798,459; 3,864,089; and 3,890,101. However, none of these known devices has proved to be completely satisfactory. Thus, there exists a need for a device which will, in a single step, automatically separate whole blood into multiple, and uniform, aliquots of plasma suitable for efficient subsequent analytical procedures.
Commonly owned, copending application Ser. No. 762,368, filed on Aug. 5, 1985, describes a device for use with a centrifugal fast analyzer which employs two sets of capillaries to avoid the problems inherent in the prior art. In this device, blood is introduced into the analyzer via a first set of capillaries which have been prefilled with unmeasured amounts of blood. When centrifugal force is applied, the blood flows out of the first capillaries into a processing chamber where it is separated into plasma and cellular phases. When the centrifugal force is released, the plasma backflows into the measuring capillaries. This device has the disadvantage that it is necessary to prefill a set of capillaries prior to processing.